Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely. This issue has been patched in version 3.1.4.
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History

Mon, 01 Dec 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 01 Dec 2025 15:30:00 +0000

Type Values Removed Values Added
First Time appeared Microsoft
Microsoft windows
Palletsprojects
Palletsprojects werkzeug
Vendors & Products Microsoft
Microsoft windows
Palletsprojects
Palletsprojects werkzeug

Sat, 29 Nov 2025 03:00:00 +0000

Type Values Removed Values Added
Description Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there are special device names such as CON, AUX, etc that are implicitly present and readable in every directory. send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely. This issue has been patched in version 3.1.4.
Title Werkzeug safe_join() allows Windows special device names
Weaknesses CWE-67
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-12-01T15:35:25.271Z

Reserved: 2025-11-24T23:01:29.679Z

Link: CVE-2025-66221

cve-icon Vulnrichment

Updated: 2025-12-01T15:35:17.228Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-11-29T03:16:00.050

Modified: 2025-12-01T15:39:33.110

Link: CVE-2025-66221

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-12-01T15:18:18Z